The present invention relates to the field of electrical coils, and particularly to a bobbin on which an electrical coil is wound.
It is common to wind coils of various shapes and sizes on mandrels (free form winding) or on bobbins. Coils wound on mandrels are generally taped after winding to maintain their shape while a bobbin provides structural support during the winding process and maintains the coil shape after winding. However, certain physical characteristics of a coil can make winding and maintaining the coil shape very difficult. The shape of any free form wound coil that has a small width with respect to depth will be very difficult to maintain during the winding process and after taping. If the coil""s depth to width ratio is greater than about 2:1 and the width of the coil is less than about xe2x85x9c inch, it is extremely difficult, if not impossible, to mold a useable bobbin for the coil. The flanges of such a bobbin are generally deformed due to insufficient cooling of the mold between the flanges. Flange deformation can prevent the coil wire from being wound on the bobbin. Flange deformation affects the shape of the wound coil and thereby it""s electrical performance. Flange deformation can also prohibit physical placement of the bobbin in its desired position and/or orientation with respect to other electrical components. In order to maintain the coil""s proper shape, the two bobbin flanges must remain flat, parallel to one another and perpendicular to the bobbin""s web after forming.
A coil bobbin manufactured in accordance with the present invention maintains the proper configuration of a fine wire electrical coil having a width that is small with respect to its depth. The bobbin is constructed from two identical halves, each having one generally flat bobbin flange, one-half of a bobbin web, a latching feature and a locking feature. The mating surfaces of the two bobbin halves are defined along the bobbin web such that each half includes one complete bobbin flange. This configuration does not require the simultaneous molding of two closely spaced bobbin flanges and therefore eliminates any flange deformation associated with insufficient mold cooling. The mating surfaces are also configured such as to prevent the fine coil wire from slipping between the mating surfaces of the two bobbin halves as the coil is wound. Latching features located on one half engage latching features located on the other half such that the two halves are held together. Locking features located on each of the two halves also engage to prevent unintentional movement between the two halves prior to winding the coil on the bobbin. The latching features are configured such that winding of the coil wire about the bobbin web positively interlocks the latches, thereby preventing them from being separated after winding.